refactor: improve build script and Dockerfile

- Translate rebuild.sh messages to English
- Add dockerfile syntax directive
- Fix heredoc syntax in Dockerfile

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

gitea_runner_java/Dockerfile

@@ -1,3 +1,4 @@
+# syntax=docker/dockerfile:1
 # Gitea Action Runner Java Image
 # 基于 gitea_runner_base 添加多版本 JDK 和 Maven
 
@@ -40,7 +41,7 @@ ENV JAVA_HOME=${JAVA_BASE}/java-17-openjdk
 ENV PATH="${JAVA_HOME}/bin:${MAVEN_HOME}/bin:${PATH}"
 
 # 创建版本切换脚本
-RUN cat > /usr/local/bin/use-java << 'EOF'
+RUN cat <<'EOF' > /usr/local/bin/use-java
 #!/bin/bash
 case "$1" in
     7)  export JAVA_HOME=/usr/lib/jvm/java-7-zulu ;;

rebuild.sh

@@ -2,19 +2,19 @@
 
 set -e
 
-# 使用说明
+# Usage
 usage() {
     echo "Usage: $0 <DIR> [VER] [save]"
     echo ""
-    echo "  DIR   - Dockerfile 所在目录路径 (必需)"
-    echo "  VER   - 镜像版本号 (可选, 默认: 1.0.0)"
-    echo "  save  - 是否保存为 tar 文件 (可选)"
+    echo "  DIR   - Directory path containing Dockerfile (required)"
+    echo "  VER   - Image version (optional, default: 1.0.0)"
+    echo "  save  - Save image as tar file (optional)"
     exit 1
 }
 
-# 检查 DIR 参数
+# Check DIR parameter
 if [ -z "$1" ]; then
-    echo "Error: 缺少 DIR 参数"
+    echo "Error: Missing DIR parameter"
     usage
 fi
 
@@ -22,35 +22,35 @@ DIR="$1"
 VER="${2:-1.0.0}"
 SAVE="$3"
 
-# 检查目录是否存在
+# Check if directory exists
 if [ ! -d "$DIR" ]; then
-    echo "Error: 目录不存在: $DIR"
+    echo "Error: Directory not found: $DIR"
     exit 1
 fi
 
-# 从目录路径提取文件夹名作为镜像名
+# Extract folder name from directory path as image name
 DIR_NAME=$(basename "$DIR")
 NAME="timi/${DIR_NAME}"
 
-echo "==> 构建镜像: ${NAME}:${VER}"
-echo "==> Dockerfile 路径: ${DIR}"
+echo "==> Building image: ${NAME}:${VER}"
+echo "==> Dockerfile path: ${DIR}"
 
-# 删除已存在的同名镜像 (忽略错误)
+# Remove existing image with same name (ignore errors)
 if docker image inspect "${NAME}:${VER}" > /dev/null 2>&1; then
-    echo "==> 删除已存在的镜像: ${NAME}:${VER}"
+    echo "==> Removing existing image: ${NAME}:${VER}"
     docker rmi "${NAME}:${VER}" || true
 fi
 
-# 构建镜像
-echo "==> 开始构建..."
+# Build image
+echo "==> Starting build..."
 docker build -t "${NAME}:${VER}" "$DIR"
 
-echo "==> 构建完成: ${NAME}:${VER}"
+echo "==> Build completed: ${NAME}:${VER}"
 
-# 如果指定 save 参数，保存镜像为 tar
+# If save parameter specified, save image as tar
 if [ "$SAVE" = "save" ]; then
     TAR_FILE="${DIR_NAME}.tar"
-    echo "==> 保存镜像为: ${TAR_FILE}"
+    echo "==> Saving image as: ${TAR_FILE}"
     docker save -o "$TAR_FILE" "${NAME}:${VER}"
-    echo "==> 保存完成: ${TAR_FILE}"
+    echo "==> Save completed: ${TAR_FILE}"
 fi